The present invention relates to an electronic musical instrument which is used to play a variety of music.
Musical instruments are roughly divided into an acoustic and an electric or electronic musical instrument according to the tone production system used. The acoustic musical instrument is one that uses natural mechanical vibrators as sound sources whereas the electric or electronic musical instrument is one that uses, as sound sources, oscillators formed by electric circuits or prestores musical waveforms in a memory and reads out therefrom the musical waveforms to generate musical signals.
Incidentally, there is a musical instrument of the type that attaches a pickup to an acoustic musical instrument and electrically amplifies its sound for reproduction through a loudspeaker system, and this type of musical instrument is considered as a kind of acoustic instrument.
In electronic musical instruments sound sources are formed by electric circuits and musical sounds or tones are output as electric signals. On this account, arbitrary waveforms can be generated by a waveform shaping circuit or the like and thus the electronic musical instrument has an advantage that it is able to synthesize sounds or tones having a great variety of timbres or tone colors.
In the ability to express player's feelings, however, the electronic musical instrument is inferior to the acoustic musical instrument. That is, the acoustic musical instrument permits the expression of player's feelings in accordance with his way of playing the instrument, whereas the electronic musical instrument, for example, a keyboard instrument, produces a sound of a pitch corresponding to the key depressed but its timbre always remains unchanged regardless of the force applied to the key, and thus the electronic musical instrument lacks the power of expression of feelings.
FIG. 1 shows, by way of example, a conventional electronic percussion instrument. A description will be given of the reason for which it is poor in the expression of feelings. Reference numeral 1 denotes a pad. The pad 1 is formed, for instance, by stretching tight a skin or a sheet of synthetic resin over a frame and has a vibro-electric converting sensor 2, such as a piezoelectric or pressure-sensitive element, attached to the back of the hide or the sheet to convert an impulse applied to the pad 1 into an electric impulse signal. An impulse waveform signal 3 from the sensor 2 is applied to an envelope detector 4, from which a trigger signal 5 is obtained.
The trigger signal 5 is input into, for example, a processor 6 called CPU, which reads out tone color data written in a specified address area of a read-only memory (hereinafter referred to as a ROM) 7. In the ROM 7 there are prestored sound data of various percussion instruments, and by reading out a specified piece of data from the ROM 7 and converting it by a D-A converter 8 into an analog signal, an electric impulse signal corresponding to the sound of a selected percussion instrument can be provided at an output terminal 11. The electric impulse signal thus obtained is applied to an amplifier/speaker system 12 for producing the sound of the selected percussion instrument through a speaker 12A. The sound data of various percussion instruments written in the ROM 7 is selected on the basis of a set value set in a setting part 13 provided in association with the CPU 6 and thus the sound data of an arbitrary percussion instrument is selectively read out of the ROM 7.
Reference numeral 9 denotes a variable gain amplifier, the gain of which is controlled by the CPU 6 in accordance with the magnitude of the peak value of the trigger signal 5 available from the envelope detector 4. That is, the gain of the variable gain amplifier 9 is controlled according to the force with which the pad 1 was struck, and consequently, the loudness of the sound can be reproduced in accordance with the force with which the pad 1 was struck.
With the conventional percussion instrument, pieces of waveform data of sounds of various percussion instruments are prestored in the ROM 7, from which a waveform data of the percussion sound selected by a player at the start or in the course of playing is read out from the ROM 7 in synchronization with his pad striking action to generate the sound. Since the timbre or tone color thus reproduced is determined by the data written in the ROM 7 regardless of the tone color which is produced by striking the pad 1, it is impossible to express the tone color intended by the player. On the other hand, in the case of the acoustic instrument, it is possible to change the tone color and the attenuation time (or attenuation rate) by changing the striking position of the pad 1, changing the material of an object for striking the pad 1, or striking the pad 1 while at the same time pressing it with a hand. Thus, a proper combination of them will permit the expression of various tone colors even with the same percussion instrument. However, the conventional electronic percussion instrument shown in FIG. 1 does not have such a function and produces only monotonous or superficial sounds set in the setting part 13. This defect is common to all electronic musical instruments.